3.5 Flashcards
What is a pathogen?
An organism that causes disease to its host
Give 4 examples of pathogens
bacteria, viruses, fungi, parasites
What are non-specific defenses in the immune system?
general defences that protect the body from any type of pathogen rather than specific pathogens
Give 3 examples of physical barriers to infection
- epithelial cells act as a physical barrier (skin)
- mucus in the nose and respiratory tract trap pathogens from entering the lungs
- cilia are small hairs in the trachea and nose that transport pathogens up and away from the lungs
Give 3 examples of chemical barriers to infection
saliva, stomach acid, tears
What is the inflammatory response?
a localised defence mechanism where damage to the tissue or infection results in the accumulation of immune cells to prevent further infection
Which cells release histamine?
mast cells
Break down the process of the inflammatory response
- injury or infection occurs
- mast cells release histamine into the bloodstream
- histamine increases permeability of the capillaries and causes vasodilation, increasing blood flow
- clotting factors and phagocytes accumulate at the site of injury/infection
What are phagocytes?
non-specific cells of the immune system that recognise pathogens and destroy them by phagocytosis
Break down the process of phagocytosis
- phagocytes recognise the pathogen
- the phagocyte then engulfs the pathogen in a vacuole
- the cell then uses digestive enzymes within lysosomes to destroy the pathogen
How do phagocytes attract more phagocytes to a site of infection?
they release cytokines
What is immunity?
the ability of the body to resist infection by a pathogen or to destroy the organism if it succeeds in invading and infecting the body
How can tears/saliva destroy pathogens?
contains the enzyme lysozyme - digest cell wall of bacteria
How can mucus destroy pathogens?
traps microorganisms - cillia can remove the mucus
How can stomach acid destroy pathogens?
destroys many of the microbes that have been swallowed
